National Weather Service United States Department of Commerce

The average date of the first freeze (low temperatures of 32 degrees or colder) typically occurs between October 7th and 17th across central and southeast Illinois.  Areas along and south of I-70 generally are in the latter part of that range, as might be expected due to its more southerly location.  The first hard freeze, with lows of 28 degrees or colder, typically occur during the last 10 days of October, although some areas may not see this occur until early November. 

The following graphics are courtesy of the Midwestern Regional Climate Center in Champaign.

Date of first freeze this season. Image courtesy MRCC

Date of first hard freeze (28 degrees or colder). Image courtesy MRCC

Average date of first freeze. Image courtesy MRCC

Average date of first hard freeze (28 deg.)  Image courtesy MRCC